Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms a part of the prior art base or the common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure herein.
Modern diesel engines are turbocharged for a number of reasons. The main reason being to improve the combustion process inside the cylinders in order to extract the maximum power possible from a given amount of fuel. Other benefits include increased drivability, increase torque, and increased engine throttle response. In the case of large trucks, more torque equates to more pulling power, which is particularly important, for example, when navigating hills or attempting to overtake other vehicles.
A major drawback of turbocharged engines is the phenomenon known as ‘turbo lag’. That is, as turbochargers run on exhaust gases, their turbines require a build-up of exhaust before they can power their compressor. This means that an engine must pick up speed before its turbocharger can kick in. Additionally, as inlet air grows hotter as it is compressed, its density is reduced, and thereby so is its efficiency in the cylinders. For this reason, a radiator-like device called an ‘intercooler’ is commonly used to counter this effect in turbocharged engines.
To help reduce turbo lag and to improve inlet air efficiency, turbocharged diesel engines utilise sealed air intake systems, incorporating intercoolers, to store residual backpressure build up by the oversupply of compressed air from the turbo, so that when the engine accelerates less work is required to reach the desired operating pressure within the intake system.
A problem with such sealed air intake systems is that if they develop leaks the forced-induction system no longer works efficiently. That is, loss of air pressure within a turbocharged intake system results in loss of engine performance, or power output. An unavoidable by-product of this loss of air pressure is increased throttle position, and hence, increased fuel usage. Increased fuel usage leads to higher operating costs, and also increased emissions due to the oversupply of fuel within the combustion chamber for a given amount of air.
Intake system leaks often start off small, which means that vehicle drivers generally tend not to notice the problem for a period of time. In fact, quite often drivers simply notice a mild change in power output, or fuel consumption, but don't necessarily associate those changes with an inlet system leak(s). Even very small leaks can lead to substantial increases in operating expenses over time. For example, if we consider a truck travelling 200,000 kilometers per year that uses 2 liters of diesel per kilometer with an intake system leak, then the required amount of fuel to operate that vehicle would be 100,000 liters. If the fuel efficiency of that truck were to be improved by as little as 5% (i.e. increased to 2.1 liters per kilometer) by fixing that intake system leak, at say $1.20 per liter of fuel, that's a saving of approximately $5,715 a year. Multiply that scenario across a fleet of trucks, and the savings are likely to be quite substantial.
Although some tools for testing to detect leaks in diesel engine air intake systems do exist, it is considered that none are convenient. A need therefore exists for improved apparatus and methods testing engine air intake systems.